In the wireless telecommunication industry, 1G, 2G and 3G to the first, second and third generations of communication protocols used for enabling communication between mobile terminals in a cellular communication network.
1G refers to the analog phone system, known as an Advanced Mobile Phone Service (AMPS) phone system. 2G is commonly used to refer to the digital cellular systems that are currently prevalent, and include CDMAOne, Global System for Mobile communications (GSM), and Time Division Multiple Access (TDMA). 2G systems can support a greater number of users in a dense area than can 1G systems.
3G commonly refers to the digital cellular systems currently being deployed. These 3 G communication systems are conceptually similar to each other with some significant differences. In a wireless communication system, it is important to improve transmission efficiency for effective transmission of data. To this end, it is important that more efficient ways of data communication and resource management are developed.
Evolution-Data Optimized or Evolution-Data only, abbreviated as EV-DO or EVDO and often EV, is a telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access. It uses multiplexing techniques including CDMA as well as TDMA to maximize both individual user's throughput and the overall system throughput.
EVDO was designed to support high data rates and be deployed along side a wireless carrier's voice services. EVDO provides access to mobile devices with forward and reverse link air interfaces that are designed to be operated end-to-end as an IP based network. Thus, EVDO can support any application which can operate on such a network within certain bit rate constraints.
The primary characteristic of an EVDO communication channel is that it is time multiplexed on the forward link, that is from the access network (AN) to the access terminal (AT) (i.e., from the base station to the mobile). This means that a single mobile has full use of the forward traffic channel within a particular geographic area (a sector) during a given slot of time. Using this technique, each user's time slot is independently modulated. This allows better service to users that are in favorable radio frequency (RF) conditions with very complex modulation techniques and service to users in poor RF conditions with simpler and more redundant signals.
The forward channel may be divided into a plurality of slots also referred to as frames. In addition to user traffic, overhead channels are interlaced into the stream. These include the pilot channel which helps the mobile find and identify a traffic channel, the media access channel (MAC) which tells the mobile when data designated for that mobile is scheduled to be transmitted over a traffic channel, and one or more logical channel (e.g., control channels) which provide other information (e.g., resource allocation data) that a mobile needs to know to properly communicate in a wireless network.
Referring to FIG. 1A, resource allocation data for a frame (e.g., an Ultra Frame (UF)) is specified in-band in the MAC header, or in a broadcast overhead channel (BOC), one frame ahead. Data in the MAC header is used by a mobile so that the mobile need not monitor the BOC if it has already decoded a packet received in a current frame. The resource allocation data transmitted over the BOC may be used by newly joined mobiles that have not had the opportunity to decode the earlier frame, or by the mobiles that monitor a logical channel which does not have data to receive in that frame. It is desirable to provide additional redundancy in the number of frames or channels that carry the resource allocation data to increase efficiency and reduce error rates cause by lost packets that carry resource allocation data.
Furthermore, in a cellular communication network, the current approach to allocating resources in a cell is to designate more resources to cells in the boundaries of a cellular zone than to the cells that are within the central area of a zone. The inner cells have over-the-air combined advantage. That is, if a mobile station is in the cell which is located in the center of a broadcast zone, it is most likely to have better broadcast signal strength because all the neighboring cells are transmitting the same signal. However, the mobile station located in a cell at the edge of a broadcast zone does not have this advantage. For the cell at the zone's edge, additional radio resources are allocated to make the same signal more reliable.
A disadvantage of the above noted approach is that since the cells in the bordering areas of the zone are designated as having more resources, the resource allocation information varies from cell to cell. That is, the same BOC cannot be utilized for all the cells in the same zone. Also, the MAC header has to be custom configured for each cell to only include the resource allocation data for that cell. It is desirable to use the same BOC or have the same resource allocation data included in the MAC header in all cells of a broadcast zone such that the signals for BOC & MAC header are identical and these signals from different cells can be over-the-air combined.